Shrew Soft VPN Client is a downloadable vpn client for windows and linux.  Its  free vpn client software from Shrew Soft Inc.
 
 

We can use this windows vpn client for :
Windows Platforms
The Shrew Soft VPN Client for Windows is a free IPsec Remote Access VPN Client for Windows 2000, XP and Vista operating systems ( x86 and amd64 versions ). It was originally developed to provide secure communications between mobile Windows hosts and open source VPN gateways that utilize standards compliant software such as ipsec-tools, OpenSWAN, FreeSWAN, StrongSWAN, isakmpd. It now offers many of the advanced features only found in expensive commercial software solutions and provides compatibility for VPN appliances produced by vendors such as Cisco, Juniper, Checkpoint, Fortinet, Netgear, Linksys, Zywall and many others.

Download the latest version of vpn client for Windows 2K/XP/Vista 32bit here
Download the latest version of vpn client for Windows 2K/XP/Vista 64bit here
Download the latest version of vpn client for Windows 2K/XP/Vista/7 here  (Development)
Download the latest version of vpn client for Windows 2K/XP/Vista/7 here  (Development)

Linux and BSD Platforms

The Shrew Soft VPN Client for Unix is a free IPsec Client for FreeBSD, NetBSD and Linux based operating systems. This version is distributed under an OSI approved open source license and is hosted in a public subversion repository. It supports most of the features availalble in the Windows VPN Client version with the exception of those which are not cross platform compatible. 

Download the latest stable version of vpn client for linux and BSD here
Download the latest development version of vpn client for linux and BSD here